On Mar 29, 2018, at 3:20 PM, Seymour J Metz <[email protected]> wrote: > > AFAIK, IBM supplied microcode on cards only for the 360/25 and for the 7090 > compatibility microcode on the 360/85 WCS. Most of the S/360 models either > were hard wired or had microcode in ROS, while the S/370 models either had > ROS or loaded microcode from 8" floppies.
My father, who was an IBM SE back in the day, told me the 360/30 microcode was on copper-clad punch cards. He said they had a customer that was using the 1401 emulation that was available on the 360/30, but they had always ordered their 1401s with a special custom feature that hadn’t been included in the emulation. IBM sent out their microcode expert who asked what the opcode was for the function. When they told him, he got out some paper, did some calculations, and announced, “If you do that, it will rewind and unload the tape drive.” They said “Yes, that’s what happens when we run our programs.” He said, “What do you want it to do?” and they described what their 1401s did with that instruction. He did some more calculating, then pulled out some blank copper-clad cards, pulled out a hole punch, punched a bunch of holes in the cards, and said, “Here, stick these in and try it.” So they did, and then their programs ran just as they had on the custom 1401s. -- Pew, Curtis G [email protected] ITS Systems/Core/Administrative Services ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
